Superregenerative remote control receiver



R. ADLER SUPERREGENERATIVE REMOTE CONTROL RECEIVER Sept. 19, 1961 2 Sheets-Sheet 1 Filed April 7, 1958 Invezz'or Robez'' c/ZalZez' ,BWM /Z orzzey- Sept. 19, 1961 R. ADLER SUPERREGENERATIVE REMOTE CONTROL RECEIVER med April 7, 1958 2 Sheets-Sheet 2 United States Patent() l 3,001,177V SUPERREGENERATIVE REMTE CONTROL RECEIVER Robert Adler, Northfield, Ill., assignor to Zenith Radio Corporation, a corporation of Delaware Filed Apr. 7, 1958, Ser. No. 726,689 '6 Claims. (Cl. 340-171) station executes some function in response to a command that is radiated from a transmitting station; indeed, it is a necessaryproperty if the system isto enjoy general appli'- cation for the Vcontrol of appliances and instruments'located within the home, garage door openers, various and sundry industrial apparatus, and the like. While the adverse effects of interference and spurious signals may be largely obviated through the expedient of a cable extend,`- ing from the control to the controlled station, the disadvantages of a cable connection far outweigh this freedom from interference and, as a consequence, systems featuring radiated commands have received much greater acceptance.

A number ofV proposals have been made for the purpose Y of obtaining freedom from false actuation in systems responding to radiated signals. One prior suggestion is disclosed in U.S. Letters Patent'No. 2,817,025 issued December 17, 1957to R. Adler and assigned to the same assignee as the present invention. That patent shows a system for remotely controlling a number of functions in a television receiver installed in a home, controlling such things ,as the on-oir" conditiongchannel selection and sound muting. It provides a comfortable margin of pro'- tection'against false actuation vby requiring that a com mand signalA f-all within a very narrow frequency range and have a predetermined minimum duration, as Well, before the controlled'device accepts and responds to it.

Another system, representing a dierent approach to the problem, is disclosed in a copending application,A Serial No. 726,718, filed April 7, 1958,:in the name of Alexander Ellett land likewise Yassigned to the same assignee as the present invention. The arrangement therel disclosed achieves protection by requiring the receipt of a command comprised of two or more signals of different'types of energy received in a particular time relation. For exv ample, the receiver may Vrequire concurrent receipt of executes acousticalfand electromagnetic signals before it a desired function.

The` Iarrangements of the subject inventionrepresent still further developments directed to protecting Va .con-

trolled station from falseoperation. They employ superregenerative Vanrplication and take advantage of certain unique properties of such ampliers, considered alone and/or in conjunction with novel microphones of un-Y usually high selectivity, to obtain freedom from false actuation with a minimum of apparatus while at the same time having a high sensitivity to radiated command signals.

Accordingly, it is an object of the invention toV provide a novel wave signal receiver featuring the use of super'-y regenerative -ampliication in a remote controly system to F r- 3,001,177 Patented Sept. 19, 1961 be actuated only in response to a received signal of a particular frequency.

It is another object of the invention to provide a novel superregenerative type of wave signal receiver of inexpensive construction `and especially suitedl for use in a remote control system.

A further and specific object of the invention is to provide Ia novel superregenerative amplier having a high degree of selectivity and eminently useful for inclusion in al remote control system which is to respond only to the receipt of a signal of a particular frequency.

v A w-ave signal receiver embodying the invention and exceedingly useful for a remote control system to be actuated only in response to a received signal of a given frequency comprises detector means including a superregenerative amplifier having a predetermined quench frequency. There is an input circuit for applying the received signal to the detector means and a control stage is coupled to the detectorfor developing a control eiect in response to the application of the received signal to the detector. The input circuit, detector and control stage constitute the signal translating channel of the receiver and `an electromechanical transducer is included in that channel for determining the selectivity of the receiver. The transducer includes a vibratory element having afreL quency of mechanical resonance which has a predetermined relation to 4the frequencyof the signal to which the receiver is to respond and means are coupled tothe signal translating channel of the receiver for responding to the aforesaidgcontrol effect.

Y A particular feature of the invention takes advantage of the unusual characteristic of a superregenerative amplier that an output signal is developed which, Vin the absence of areceived signal, includes components having a frequency distribution representing noise but which, in i Another feature of the invention, pertaining to the con-v f struction of a highly selective superregenerative amplifier,

` tube as a mechanism Ifor concerns the use of an electromechanical' transducer including a vibratory element, such as a magnetostrictive rod .hav-ing a mechanical frequency corresponding to the desired signal frequency, in the grid circuit of the amplifier converting a received acoustical signal into an electrical counterpart for amplification. The extraordinary Q or selectivity of such a transducer imparts a like selectivity to the amplifier. Y

The features of the present inventionwhich are believed to be novel are set forth with particularity in the appended claims. The organization and manner of operation of the invention, together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in the several ligures of which like reference numerals identify like elements, and in which: y

FIGURE l is a block diagram of a superregenerative receiver constructed in accordance with the invention;

FIGURE 2 includes characteristic curves employed in explaining the operation of the receiver of FIGUREY l;

FIGURES V3 and 4 represent, partly schematically and partly in 1a block diagram, other'superregenerative receivers embodying the teachings of the subject invention;

FIGURE 5 is a circuit diagram of a modified form ofV which may be used in substitution for a different form of Vcycle .are not permitted to achieve'eq s,oo1,177

ltransducer employed in the arrangements of FIGURES 4l and 5.

Before considering the receiver of FIGURE 1 in detail, it is appropriate to comment generally upon superregen- V,erative receivers particularly as to their two welll-recog nized but different modes of operation. Essentially, such a .receiver comprises a regenerative oscillatory circuit -yyhich is controlled by quenching to have alternately .posi- `tive and negative values of conductance, the-.quenching Vbeing under the influence of an externally supplied signal f ,or an internal `effect Within the receiyer and occurring at a frequency low with reference to the operating frequency of the receiver.V In onion lo achieve Stable operating ccndiiions, the control of the .regenerative circuit by.. the quench `signal `such that the circuit conductanceg inte.-

1sraierl, over a period of tinfie lons with vrespect to the Period i' ille. quench signal, has a nosiiiye Ynllla "Ill-e inode oscilla.tions` 'lnlilo nn'. ineach negative conductance interval toi an equilibrium vaille before lacingquenched- In the'linear'nioderhowever, the

U .lbiinnr .or saturallollleiel before brina encircled Thus,inhoth modes, transient oscillations are devel?,

oped'prepresenting'bursts, of lenergy atthe oscillatory free naar of 'fhefeeivar'ad anni a, ne. renting f frequencylf VThe amplitude of the` exciting signal at the atari of( each'. negative conductance interval. ieierrninee 110W' quickly 'oscillations build. ini!v ln. ine logarithmic inode, the amplitude of the signal being amplified deterl mines the portion ofthe negative conciuct'anee interval over which equilibrium conditions persist; in the speciai case of self-quenched operation,the may determine the quench frequency.VV In fthelinear mode, on

lthe other hand",v wherein quenching prevents the`attainment'. of equilibriumconditions, thefiinal amplitude oscillation in eachquench'cycle manifests the a'irplitude of the applied signal' at the start of thatz'particular cycle. Accordingly, thetransient'oscillations of Veach mode re ectror manifest the amplitude variations .of received v signal and permit the signal modulationto be" recovered,

by detection. In the logarithmic'mode, ldetectie may Vbe accomplished Withinthe superregenerator its ortho oscillations may be-supplied toa separate detec or. For

linear-mode operation', oscillations are ai separatel sj'tage.'i o

Mentiofshould be made of oneVV further characteristic` of a logarithrnicamode superregenerator is taken advantage of in the arrangement of FIGURE 1.` In par-V ticular, that" type receiver develops an output signal representingV random noise in quench cycles oocurr'ing 'infthe 'absence of a, received signal. `rIn the presence of an unmodulated received signal, however, Where the received signal amplitude is largefcompared to the' circuit noise level, ythenoise output signal ofthel detector falls to zero.

Considering the arrangement of FIGURE l no vy` more particularly, the receiver there represented has an input circuit for applying a received signal to a detector lincluding a superregenerative amplifier. This receiver may re-lV spondto a variety ofl forms o'fsignal energy and may for example, be conveniently employed in a system in vvhich Y the, radiated command vsignals are acoustical or electro- -magnctio Fonconvcnience. and4 in orderto describe aspecitc embodiment, it will beassumed that the system under considerationfeaturcsthe use of commands inthe.

forin of radiatedacoustical energy. Accordingly, the input circuiti compriseswa Sonie receiverY or microphone 1,0

Wlichffrn'aybe Of'ille. oleolroalaiiciyreandlra filter '11 to.l

which. the output terminals of the o microphone connect.

The." flessen?! oliaraoleriolics of; the .filter may. be, relied.. upon to impose any desired degree of selectivityupon the,-

minori-.ione arianne, Selecting/.is einen. in. accordance Wiilrlls regulierement-,flier Rauicnlar; installation.

reoelvcniienendina anon. in operation conditions and. ir.- Y

' olii? Parameters incr nare. a logarithmic or a linearmode vofA operation,-V In the i-ogarithrnicfor saturation level ,s in any quench `Filter 11 is connected through a buffer amplifier 12 to detector means including a superregenerative amplier 13 and a wave signal detector 14 which may be a crystal diode. The superregenerator is .of conventional construction and may be supplied with a quenching signal from an external source or it may be of the self-quenching type. Coupled in cascade to detector 14 are a low-pass filter 15, a control e stage 16 and a controlled device 17. Filter 15 has a cut# off frequency which isl less than the quench frequency of superregenerator 13,.and control stage 16 is arranged to develop a control effect upon interruption of the noise signal output received from detector 14 through filter 15.

Structurally, stage 16' mayvconstitute a grid leak detector `,and a relay connected into-its anode circuit.

In considering the operationof this. receiver,`reference is made to the characteristic curves of FIGURE 2. wherein curvev A represents the distribution offenergyin the output signalV of the superregenerator inthe absence of a received unmodulatedsi'gnal. The curve illustrates a random noise output, that is, lan, output including components yhaving a vfrequency distribution representing noise. The ordinate fsy represents the oscillatory frequency Vof the amplifier which, l.` i

of course, is high relative to thequench frequency.

Actually, the energy is contained in bursts of. transient oscillations occurring at the quench frequency and, after ldetection-iny detector 14, the noise frequency components are` applied to lowmass filter 15- All'snch noisecornpofnal when struck at Va free end. The physical length o f the nents within the pass band of the filter are translated to control stage 16, but that stage does not actuatecontrolled device 17 in response torthis noise, signal. yOf course, the output of detector V14 will also include a strong component at the quench frequency but .that componentV is not passed by filter 15.

command signal is radiated from a controlling point to the receiver of FIGURE l. Since the system has been assumed to be one employing acoustical or soniclenergy,

the transmitter may conveniently be of the type described in ILS. Letters Patent 2,821,954 issued February 4, 195 8 to R. Adler and assigned to the same assignee as the presf sent invention. .-Essentially; itis a longitudinal-mode v-ibrator, such as a steel rod, which issues'ian acoustical sig rod in relation to the velocity oto-"Wave propagation therein determines the frequency of the radiation'` whichrwill, of course, be assumed tobe. within the acceptance Aband of "microphone 1 0 and ilter 1,1 at thereceiyer. rIlia rod; has

relatively low internal damping so that, the command is in,

' thefforni, of av pulse of substantial time duration,- The I ther frpm somewhat from the resonant frequency of theu superre-KV generator.

' The other vertical( bars of FKfUREl 2v represent the bunching or concentration of the energy oft-hesuperrcgenerator at pointsin the frequency spectrum whichJhave a spacing mlf from the. signal frequencyjg equal to irt-y tegral. multiples, of the quench frequencyy including theA Vinteger- 1;. This, assumes that,` the amplitude of.: the re-..

acived Signal islargc with respect to the inherent. oninternnl. naine-,- which otherwise initiates oscilla., within kthe superregenerator,l The total energy in. each quench; cycle., e. Sarnano inY the absence. ci signalent its.

the, reociyeof command; is

frcanoncrl of' and;

When it is desired to actuate controlled device 17, a Y

Yio the frequency. Spectrum. is. rnnohVA differentno signal through filter 15fto control stage 16." In other words, the noise signal applied to control stage 16 in quiescent operating conditions is interrupted and stage 16 responds to the interruption to develop a control effect which is applied to device 17 to cause it to per-form a desired'function. If stage 16 is a grid-leak detector, a control action'is produced because such a detectorexperiencesan increase inplate currentwhen the signal applied to its grid is interrupted.

`"I'he invention -is not particularly concerned Witlvithe naturewof the controlled function executed by device 17. The controlled device may be a motor thatr is turned on or off; it may be a television receiver controlled as to onotf, channelselectiommuting, volume; and such like.

The arrangement of FIGURE l? is necessarily restricted to'accomplishing a 'single control function for the simple reason that control lstage 16 initiates the control upon interruption of the noise signal output of detector 14 and interruption of the noise signal is experienced upon the reception of anyr sign'al havingy a frequency within the acceptance band of thefreceiven There is no other unique requirement as.ltomfrequency;` Freedom fronioperation in response to spurious signals thatmay bepresent in the location of -the receiver isv determined by the selectivity imposed by-microphone and itsfllter 11 Vand is selected with regard to'the environmentV in which the receiver is to be used. A very highl degree lof selectivity may result by employing a pick-up device or-V microphone in the -forrn of an electromechanical transducer in place of units 10 and 11'. Infact, such a transducer mayso restrictthe acceptance of the receiver that it responds only-to a command signal of one frequency. Further consideration is given hereinafter to the structural features of such a microphone.

A modified form of receiver is represented in FIG- URE 3. It distinguishes from Vthe receiver of FIGURE v1 in that it has the ability to respond to a'plurality of command signals and selectively accomplish any one of sev-v eral control functions, distinguishing therebetween in accordance with some characteristic suchv as the frequency of the command that is received. I Y The receiver there represented comprises a broadband electrostatic microphone A10 coupled to the-input circuit ofbuffer amplifier V12 including a triode tube 20 having an anode, cathode, and control electrode. 'Micro-I phone 410 is connected tothe control electrode through a coupling'condenser 21 and a grid resistor 22. An R-C type biasing network 23 connects the cathode of tube 20 to ground and the anode of the tube connects toa source +B of :operating potential'through a resistor 24. vThe high-potential terminal of microphone 1t) is connected to sourceA +B through series resistors 25, 26 and their common junction is grounded through a by-pass condenser27, '1 Y The buffer amplifier connects to a self-quenching selfdetecting logarit-hmic-mode superregenerator 13 including another triode tube 30. The associated circuitry connects this'tube intoan oscillatory circuitrofthe Hartley type, in which the operating 'frequency is determined by a resonant or tank circuit including an inductor 31, a condenser 32, and a resistor 33. Self-quenching .action is under` the control of self-biasing resistor-condenser network-34 connected in series with the control or grid electrode of tube 30. The anode of tube 30 connects to the source -l-Brof operating potential through a resistor 29 and a condenser 35 provides a partial returnfor 'the A.C. anode current. A received signal may be applied to the supreregenerator from buffer amplifier 12 through a coupling condenser' 36 and the detected output is delivered to an amplifier and frequency converter 37 through a coupling lcondenser 38.V Unit 37 may be a single tube stage employing'a multi-grid tubehaving a self-oscillatory section'and a converter section. f For example, Yit may be of the well-known pentagrid variety. Alternatively, it may have separate stages of amplification and frequency con- Aid version, if desired. In order to effect frequency conversion, unit 37 must include a heterodyne oscillator if the conversion is to be a subtraction rather than division of frequency. Thep'urpose of frequency conversion is to p'ermit the useofradiated command signals of certain assigned frequencies to` effect remote control through the agency of 'devices that are highly selective as to frequency and, preferably` respond 4to signals which are much lower in frequency than the command signals. These devices, ofcourse, correspond in number to the number of command signals to be employed and have such frequency relation'to the commandV signal frequencies that the simple process of heterodyningthe detected output of the superr'egene'rator derives signals for actuating them. If the system is intended to respondto three command signals, individuallyhaving an assigned frequency, the filter arrangement 15 Amay, comprise three electromechanical transducers 40, 41 and- 42 fof the m-agnetostrictive type. Such a transducer iachieve -a desired frequency of mechanical resonance. A permanent magnet 43 provides the necessary magnetic bias to the rod and a pair of coils is wound on spaced portions of each rod as a core. One coil of each pair is employed for excitation and the excitation coils are connected in seriesv inthe anode circuit of the output tube of` ingone from the other and directing the execution of controlled functions in accordance with the frequency of the commandthat'happens to be received. fIt also is distinguishable from FIGURE l in that the control accomplished is in response to an amplified output signal from the'detectorA rather than an interruption in its noise output. In operation,lmicrophone 10 intercepts the command signal and applies it to superregenerative detector 13. A greatly amplified detected output signal of the same frequency as the receivedsignal is applied to unit 37 "for further amplification'and for conversion in frequency to correspond to the mechanical resonant frequency of the particular one of transducers 40-42 to be controlled by the received command. Theconverted signal, in traversing the excitation coil of the transducer having a frequency of mechanical resonance equal to that of the applied signal, establishes a mechanical stress Wave which traverses the magnetostrictive element and induces an output signal in the pick-up coil thereof. That signal is'delivered to controlled device 17 which executes the function controlled by the input circuit to which the signal has been applied.

vBuffer amplifier 1 2 isolates the superregenerator from microphone 10 as protection against the establishment of coherent oscillations which may otherwise be experienced if the superregenerator is vpermitted to actuate the microphone Yas'a radiator, emitting radiations that may in turn be reflected back to the pick-up device and continue excitation of the detector. The amplifier of unit 37 performs a related function, isolating filters 40-42 from the superregenerator. Without such isolation, coherent oscillations may be established which would mask received signals and render the receiver effectively inoperative.

The system of FIGURE 3 accommodates a plurality of command signals to control a series of highly selective includesa rod of magnetostrictive material, such as nickel, having ay physical length adjusted to mecha .2., they fell within .the frequency Spacing Afllie; assures; appropriate frequeuey Selection by thetraus.- Queers without vertical interference., `The heteredynins etennmvided by unitv 37V as, eaplaiued above, permits treque -Se1eetive titers 40:42.10 operate at lower frequeneies than the'received .cemnuuwll` .Signals in order that they may have lOWer values. ef Q and Wider; frequency separation, It is neeessarnheweventhat theecuyerter eseillatet be Stable andv be arranged te avoidreaetion upon. the Sunerregenerater 1 Simpliteation and some .reduction in the number ofV circuit `components.,requiredy may result from the utilization of multigrid-,multipurpose tubes which anual;A fer example., provide, .within the one envelope, the yfunction of buffer amplifier 12, and the superregenerative, detector. In any` such combined stage, it is necessary that the buffer.A section be, in ei'ie'ct, isolated from the superregellcratonsection in order to safeguard-.against coherent oscillations. .This may be accomplishedrby' having the butter and Sunerresenerater fseeteusaet upon diterent and. snaeed Portions f the electron Stream. with Stray interelectrode coupling minimized,

, A linear-.mode type of superregenerative amplifier of particular application to receiver apparatus for a remote control system intended to be actuated only in response tg the `reception of a signal of ai particular Iirequenc-y is shown in FIGURE 4. It includes @electron-discharge device 50 having an anode,` a cathode anda control electrode`,lalthough Vit may be part ofa multifunction, multis the amplitude of oscillations obtained in any quench cycle grid tube it desired. The circuitry associated with the v tubeior the purpose' of constituting `an oscillation gen erator` comprises ayresonant circuitformed of an inductor 51 and a condenserZ. This circuit is resonant at the desired operating frequency and is inductively coupled to a grid coil 53 as indicated symbolicallyat M. r[lie quench signal source 54, in .this instance, is external to the arn-V pliler and isfthe sole source of operating potential prO.- Ydcd.- It isy coupled to the amplifier bymeans of a coupling transformer 55, across the secondary of which is connected a by-pass condenser 56 andai potentiometer 5,7. Oneterminal of the transformer secondary is connected to. the anode of tube 5.0 through tank circuit 51, 5.2 and the other is connected through a tap of potentiom-` eter 5,7 and an adjustable cathoderesistor 58 to the cathe ode. The grid circuit of tube 50. includes, in VVaddition toV coil 53` and the usual grid condenser 59,l and resistor 60,` a coil 61 .and is connected to` the electrical center of the secondary winding of transformer 55.

ceived acoustical signalsrestablish, through magnetostrio tive conyersion, an electrical signal in series in the gridV circuit of the amplifier. The outputl signal of the ampliiier is delivered through a couplingfcondenser 65 to` a detectorf14iwhich, in turn, supplies detected signals to a l control stage 76. having an output circuit coupled to the control circuit of controlled device 17.` Any of a variety of detectors, suchY as grid-leak or diode type, may be ernployedas unit 74 but the time constant should be long this embodiment is a threshold device which translates an` applied` signal provided that its amplitude exceeds a minmum. value! 1 11- operation, a corinfrn'anndA signall transmitted to the re-` eeiyer.' irl` the forro. et acoustical radiation impinses upon. the selective4 Pieltfun device 6.1 62. and' establishes. a. l stresser/,aye therein Se long as the. f..re.quer,1ey ef. the eeneradiation is very elpee .te the, frequency et mechanical resonance of theV magnetostritor.0 The me ehaueal stress wave induces an electrical signal in. coil 6,1 and this signal is applied tothe amplier. The amplifier, undfl the `influence,of the quench signal `from source 54, experiences 'successive conditions of negative and pesi-Y tive conductance characteristics of superregeneration but the. oscillations are not permitted to achieve saturation or equilibrium value in any quench cycle; in other words,l 'the Yamplifier is controlled to operate in thelinear mode. The, 1,0

presence of the received signal, assumingit to have `an amplitude exceeding the noise level-of thesystem, causes tok be high with respect to that produced in the absence. of the received signah i Accordingly, the output signal of detector 74 hasv substantially greater amplitude in the presence of sign-al.. It will readily exceed the threshold, amplitude of the associated control stage 76 actuation of controlled device 17. Y l For this circuitlto yield.satisfactory'performance, it is necessary thatv nooscillation current flow throughjthe.

coil otthe` magnetostrictive microphone because, WSW. would lead; directly to'a condition of ,continuous coherentoscila that/to occur, the .low damping ofthe microphone lations. vAny such condition would mask the reception oi the received signal and disable the system.vv .Tlf-hat is avoided in the described arrangements by the particular location of coil 61 inV series in the gridl circuit whereno oscillator current flows. Itis also necessary that the Vquenchfrequency be very low in ordervthat ringing of the tank circuit `51,- 5.2 upon termination` of the received signal, may be permitted to decay down to the noise level.

Qtherwise, asingle actuating signal wouldr result in con-j. tinuous coherent oscillations and destroy 'the systemfs.

sensitivity. This requirement may for instance, be satised if the quench signal is a 60 cycle signal obtained from a commercial power supply. This has the added benefitof eliminating the requirement forV a separate 'quench signal source.I A suitable frequency for the sonic energy is in the neighborhood of 40 kilocycles. ,l Itis further necessary, if linear mode operation isto be achieved, to maintain a closely controlled rate of ame 'plitude build-up within the superregenerative ampliiier.

This is accomplished by the generoususe of degenerative feedback resulting from cathode resistor 58j. The dy-A namic transconductanceoftube is held to a very small fraction, in the order ottone to five percent', of its normal transductance. during the active part of the quench cycle to assure the necessary stability. Moreover, the low frequency, of operation enhances thestability andl permits with respect tothe quench period. The cont-rol stage in operation withoutthe isolation provided'by a separate ine put buffer amplier. Y Y

Where the quench signal from the external source is of sinusoidal waveform, the changefrQrn` positive to negative conductance occurs as the quench signal crosses its A.C., This is the` portion of; the waveform which has, the

greatest slope.V "The .resulting-transient tends to shock-V excite tuned circuit 51;, 52 at the instant plate current starts willow.; If this. condition is permittedl to, prevail,l the operation of the receiver is greatly impaired. Shock excitationfmay be eliminated by the modification of the amplifier represented in FIGURE 5,. In this modication, a delay is introduced in the application of the quenching signal to the anode of tube 5.0 relative to the application. of thej quenching, signal 'to the cathode. The delayisI achieved by a network including a resistor 701 and, acond'enser 71p. The arrangement of FIGURE 5 -further includes neutralizing networkin the grid' circuit. provided.

by 'an R-C network '7.2. This amplifier operates in precisely the same fashion as, the amplier of FIGURE4 4. while, at the same time, avoiding the tendency to Shock excitation resulting from transient elects as the circuit.; conductance changes from positive. to negative. In the, arrangement. of FIGURES, the, eathode. potential of tube 5.0, becomesy negative betere thetime delay networlt 7th.-V

'71 Permtame, snede te, beeemenesitire. For thiscoadi-` and effect.

tion, a Smau amount of gna surreal is established, a1-

thoughjn'ot at the Vsignalfrequency because oscillations annot'commence until the anode potential is positive. Within ya relatiavely few electrical degrees, the anode potential becomes positive and oscillations are permitted tobeestablished.

f Inthis circuit, as in the embodiment shown in FIGURE 4,'the ow of electrons to the grid during the period of oscillation'is prevented by cathode resistor 58 andby the high series resistance 6); the flow of capacitive current through coil 61 is neutralized by network 72.

f A-s'uperregenerative receiver inthe form of FIGURES 4 and 5 is a single-signal device and responds. only to command signals `at. aufrequency very close to the'frequencyfgof mechanical resonanceA of the magnetostrictive 'microphone Other forms Vof Vhighly selective microphoneV may -be utilized, such as` that represented in FIGURE 6, where the microphone is a two-part passive vibratory element 77, 78 -With a centrally-positioned piezoelectric wafer 79. The passive elements 77, 78 may be sections of steel rod having a length selected in accordance ,with the velocity of wave signalpropogation therein to achieve the desired mechanical resonance frequency. This'device is a longitudinal-mode vibrator and the interposed wafer 79 is secured, by soldering, to the contiguous ends of vibrator sections 77, 78. The wafer is preferably constructed of a material having a high electromechanical coupling factor and may be formed of any of the titanate mixtures, especially bari-um titanate.

Electrodes are provided on its opposed surfaces forming the rinterfaces with rod segments 77, 78 and leads. extend from the electrodes to facilitate connecting the ,microphone in seriesA with Vthe grid circuit of the amplifier. Wafer 79, moreover, has a` past history of polarizing such that it retains a remanent polarization in the longitudinal direction; This microphone lends itself to temperature compensation;` the vibrator material and piezoelectric' material'may have compensating temperature coefiicients sol that the microphone is stable in the face of temperature changes. It is also possible t0 use rods or wafers of` barium titanate in a piezoelectric microphone. Where such rods or wafers are employed, an electrical signal is derived through the agency of electrodes provided thereon.

The described structures all take advantage of the unique properties of superregenerative circuits, and, through utilization of the highly selective magnetostrictive or piezoelectric microphones, may be exceedingly selective. This affords substantial freedom against false actuation through a receiver construction that may be quite inexpensive. For example, units 12, 13 and* 14 of FIGURE l may be provided by a single-tube circuit. Although tube circuits have been disclosed, the transistor equivalents are just as suitable for use as superregenerative amplifiers. Certain features described in this application are described and claimed in copending divisional application Serial No. 63,878 filed October 20, 1960 by Robert Adler for Superregenerative Remote Control Receiver and assigned to the same assignee as the present application.

While particular embodiments of the invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and, therefore, the aim in the appended claims is to cover all such changes and modifications as fall within the true spirit` and scope of the invention.

I claim:

l. A wave signal receiver for a remote control system to be actuated only in response to a received signal of a given frequency, said receiver comprising: a superregenerative amplifier including an electron-discharge device having a cathode, a control electrode and at least one other electrode and further including associated circuitry constituting with said device an oscillatory circuit; a quenchsignal source external to said amplifier for supplying a quench signal, having a frequency low with respect to the oscillatory frequency of said circuit, to effect conductance variations therein for the purpose of establishing superregenerative amplification of the linear-mode type; :frequency-selective means, responsive substantially only t0 said received signal and connected in series with said control electrode in said oscillatory circuit, for applyingv said received signal to said amplifier; a control stage coupled to said amplifier for deriving a control effect in response to said received signal; and means coupled to said control stage for utilizing said control effect.

2. A wave signalzreceiver for a remote control system to be actuated only in responseto a received acoustical signal of a givenfrequency, said receiver comprising: a

superregenerative amplifier including an electron-discharge device having a cathode, a control electrode and at least one other' electrode and further 'including associated circuitry constituting with said device an oscillatory circuit; aquench-signal source external to said amplifiery for supplying a quench signal, having a frequency low with respect to the oscillatory frequency of said circuit, tov effect conductance variations therein for the purpose of establishing superregenerative amplification of the tern to be actuated only in response to a received acoustical signal. of a given frequency, said receiver comprising: a superregenerative amplifier including an electrondischarge device having a cathode, a control electrode i and atleast one other electrode and further including as-' sociated circuitry constituting vwith said deviceran oscil-V latory circuit characterized by the fact that no oscillatorcurrentfiows in the circuit of said control electrode;V a quench-signal.source` external to said ramplifier for supplying la quench signal, having a frequency low with respect to the oscillatory frequency of said circuit, to effect conductance variations therein for the purpose o-f establishing superregenerative amplification of the linear-mode type; an electromechanical transducer, including a vibrator element having a frequency of mechanical resonance corresponding to said given frequency, connected in series with said control electrode in said oscillatory circuit for applying said received signal to said amplifier; a control stage coupled to said amplifier for deriving a control effect in response to said received signal; and means coupled to said control stage for utilizing said control effect.

4. A Wave signal reeciver for la remote control system to be actuated only in response -to a received acoustical signal of a given frequency, said receiver comprising: a superregenerative amplifier including an electron-discharge device having a cathode, a control electrode and at least one other electrode Vand further including associated circuitry cons-tituting with said device an oscillatory circuit characterized by the fact that no oscillator current flows in the circuit of said control electrode, said associated circuitry including a cathode resistor providing degeneration such that during negative-conductance intervals of said amplifier the transconductance of said device is but a small fraction of its maximum value; a quench-signal source external to said amplifier for supplying a quench signal, having a frequency low with respect to the oscillatory frequency of said circuit, -to effect conductance variations therein for the purpose of establishing superregenerative Iamplification of the linear-mode type; an electromechanical transducer, including a vibrator element having a frequency of mechanical resonance corre effect.

V11 sponding to said given frequency, connected in series with said control electrode insaid oscillatory circuitfor applying said received signal toJsaid amplien a control stage coupled to said amplifier for deriving a control effeetY in response -to said received signal; and means coupled to said control stage for utilizing Ysaid control v 5r. Awave signal receiver fora remote control system 4to'ibe actuated only inresponseto a received acoustical signal of'a given frequency, said receiver comprising: a superregenerative 4amplifier including -an electron-discharge device having a cathode, awcontrol electrode and at least one-other electrode `and further including associated circuitry constituting withsaid device an oscillatory circuit characterizedlby the vfact that no oscillator current flows in the circuit of saidcontrol electrode,

, said associated circuitry including 4a cathode resistor providing degeneration such thatV during negativeconduct-Y ance. intervals; of said amplifier ythe transconductance oi saidrdevice is but a small fraction of `its maximurnvalue;

a .quench-signal source'external to said amplifier, con` stituting the sole source of excitation potential of said oscillatory circuit, and supplying between said'rcathode and other electrode `of said device a quench signal, having Va'requency low with respect to the oscillatory hsequency of said circuit, to eiect conductance variations therein for the purpose of establishing superregenerative amplification` of the linear-inodetype; an electromechani` cali transducer, including a vibrator element having a frequency of mechanicall rresonance corresponding ,to said given frequency, connectedin series with said' control electrode in saidloscillatory circuit for applying said recived signal to said ampliena controlv stage coupled'- to said amplifier for deriving a control effect in response to said received signal; and means coupled to said control stage for utilizing said control effect,r i

I 6,. A wave signal receiver for a remote control v,system tombe. actuated, only .in response t-o a received yacoustical sig-nal ,ofga Vgiven frequency, said'receiver comprising: a superregenerative ampliierV including 'an electron-dischargerdevice having a cathode, a control electrode and at least one other electrode and further 'including' associaiuola?? v 12Y ated'circu-itry constituting with said device jan oscillatory circuit characterized by the fact that no oscillator eurrent` ilowskin the circuit of said controlk electrode,- said associatedcircuitry including a cathode resistorproviding degeneration suchV thatV during negative-*conductanceintervals of said amplifier the transconductance of saidv device is but a small fraction of its" value; a quench-signal source external to said amplier, co`nstitu-tfing the sole source of excitation potential of saidV oscillatory circuit, for supplying -a'quench signal, having a frequency low with respect to the oscillatory frequency of said circuit, to eieot Yconductance variations therein for the purpose of establishing a superregenerative ampli'- ication of the linear-mode type; means, includingra time# 1 delay device, for connecting said' cathodey andlother electrode across said-source and -for delaying potential variations of said other electrode relative to related-po-4 tential variations of said cathode; an electromechanical transducer, including a vibrator element havin-g. la frequency of mechanical resonance corresponding :to-said given frequency, connected in series with said control electrode in saidy oscillatory circuit for applying said received signal to said amplifier; a control stage coupled to said amplifier for deriving a control effect in response to said received signal; and means coupledjto said control stagefor utilizing said controlelect.

YReferences Cited in thetileof this patent.l j UNITED STATES PATENTS 

